1. Field
One embodiment of the invention relates to a projection display apparatus and a controlling method for the projection display apparatus.
2. Description of the Related Art
A projection display apparatus (projector) is a display apparatus that displays image information on a large screen. In the projection display apparatus, light which is emitted from a light source such as a high-pressure mercury lamp is modulated by use of a modulator such as a liquid crystal panel, and is projected on a screen through a projection lens. Since the light source lamp of the projection display apparatus generates a large amount of heat, the lamp needs to be cooled by a cooling fan.
The rotation speed of the cooling fan is generally set according to temperature. However, depending upon the temperature at start-up, the cooling fan may not be able to start normally. Jpn. Pat. Appln. KOKAI Publication No. 2006-301279 discloses an image forming apparatus such as a laser beam printer which, immediately after the apparatus is started, controls rotation of a cooling fan of a fixing roller to shorten a preheating time for the fixing roller. In the image forming apparatus, a drive voltage that is approximately twice the normal drive voltage is applied to the cooling fan for a preset period of time after the power source is turned on. Since the fixing roller needs to be preheated, the cooling capacity becomes to be lowered, when the preset period of time has elapsed, by setting the drive voltage of the cooling fan lower than the normal drive voltage.
Generally, grease is used as lubricant for a fan motor of a cooling fan in a projection display apparatus. When the projection display apparatus is used in low temperature environment, for example, below the freezing point, the grease is cooled to be hardened and fixed, which obstructs the rotation of the fan in some cases.
With the above technique, the drive voltage of the cooling fan is set higher than the normal drive voltage immediately after the power source is turned on. However, in the temperature condition which allows the cooling fan to be driven normally, it is not necessary to enhance significantly the drive voltage of the cooling fan immediately after the power source is turned on.
Further, with the above technique, the drive voltage of the cooling fan is set higher than the normal drive voltage only for the preset period of time after the power source is turned on. However, in the case where the apparatus is used in the low temperature environment, the hardened and fixed grease may not be softened enough even though the drive voltage is raised for the preset period of time and, failing to normalize the cooling fan in some cases.